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Introduction to databases and Relational Model

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Databases Topic 1 Quiz

Questão 1 de 16

1

What do the privileges associated with your role (the STUDENT role) allow you to do?

Selecione uma das seguintes:

  • Create tables

  • Drop tables

  • Create triggers

  • All of the above

Explicação

Questão 2 de 16

1

Foreign keys in the relational model make it possible to:

Selecione uma das seguintes:

  • Maintain entity integrity

  • Create unique records

  • Open the back door of the house when we have lost our primary key

  • Create relationships between tables

Explicação

Questão 3 de 16

1

A database may contain __________.

Selecione uma das seguintes:

  • tables.

  • metadata.

  • triggers.

  • stored procedures.

  • All of the above.

Explicação

Questão 4 de 16

1

You need to create a column in a table that will store numbers in the form nnn.xx (e.g., 145.67) What data type is this?

Selecione uma das seguintes:

  • NUMBER(5)

  • NUMBER(5,2)

  • FLOAT(3,2)

  • NUMBER(3,2)

Explicação

Questão 5 de 16

1

The relational model __________.

Selecione uma das seguintes:

  • was first proposed in the late 1960's/early 1970's

  • was developed by E.F Codd

  • was developed at IBM

  • resulted in the DBMS product, DB2

  • All of the above.

Explicação

Questão 6 de 16

1

What is the main difference between the Oracle SQL data types VARCHAR2 and CHAR?

Selecione uma das seguintes:

  • CHAR is variable in length

  • CHAR allows for numbers and text

  • VARCHAR2 is variable in length

  • VARCHAR2 has a maximum length of 255 characters

Explicação

Questão 7 de 16

1

Which of the following is NOT a property of a valid relation?

Selecione uma das seguintes:

  • All tuples must be unique – i.e., there must be an attribute or set of attributes that uniquely identifies each row

  • Each attribute in a relation has a distinct name

  • Attributes and tuples are not ordered

  • Each relation must contain data

Explicação

Questão 8 de 16

1

A null indicates:

Selecione uma das seguintes:

  • A numeric value with value 0

  • The absence of a value

  • A very small value

  • An erroneous value

Explicação

Questão 9 de 16

1

In the relational database terminology, a table is synonymous with:

Selecione uma das seguintes:

  • A relation

  • A row

  • An attribute

  • A column

Explicação

Questão 10 de 16

1

In the relational database terminology, a tuple is synonymous with:

Selecione uma das seguintes:

  • An attribute

  • A column

  • A relation

  • A row

Explicação

Questão 11 de 16

1

Data models have the following features:

Selecione uma das seguintes:

  • Structure, operators, constraints

  • Entity integrity, referential integrity, domain integrity

  • Relations, attributes, tuples

  • Relational algebra, relational calculus, SQL

Explicação

Questão 12 de 16

1

What SQL command would you execute in Oracle to show the structure of a table called Workshop?

Selecione uma das seguintes:

  • DESCRIBE Workshop;

  • DEMONSTRATE Workshop;

  • SELECT * FROM Workshop;

  • SHOW Workshop;

Explicação

Questão 13 de 16

1

An unknown value is indicated by:

Selecione uma das seguintes:

  • The string of characters "null"

  • The null "value"

  • The value 0

  • The string of characters "TBA"

Explicação

Questão 14 de 16

1

A relation that contains data recording Murdoch students' performance in units, has the following attributes:
(StudentNumber, StudentName, UnitCode, Year, Semester, Grade, Mark).

What would be an appropriate primary key for this relation?

Selecione uma das seguintes:

  • (StudentNumber)

  • (StudentNumber, UnitCode, Grade)

  • (StudentNumber, UnitCode, Year, Semester)

  • (StudentNumber, StudentName, UnitCode, Year, Semester, Grade, Mark)

Explicação

Questão 15 de 16

1

In the relational database terminology, an attribute is synonymous with:

Selecione uma das seguintes:

  • A relation

  • A column

  • A table

  • A row

Explicação

Questão 16 de 16

1

Which of the following statements does NOT apply to relational databases?

Selecione uma das seguintes:

  • Relational databases are simple to understand

  • Relational databases have a strong mathematical foundation

  • Relational databases have a strong procedural orientation

  • Tables are one of the basic components of relational databases

Explicação

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